“If something happens, you don’t want to be thinking about what you are going to do — you already know what you are going to do. When I saw that left turn with a direct heading, I instinctively knew he was heading for an airport.”

The airport in question would have been Pulau Langkawi, an airstrip 3962 metres long with no obstacles and an approach over water.

Members of the social group Christian Muslim Alliance Pakistan take part in a candlelight vigil for passengers that were aboard a missing Malaysia Airlines plane. Photo: AP

Goodfellow wrote that the plane's captain, Zaharie Ahmad Shah, would have chosen this strip over Kuala Lumpur International Airport because the plane would have had to cross high ridges.

The electrical fire also explained why the communications systems went down, and in a separate order, Goodfellow wrote.

“For me, the loss of transponders and communications makes perfect sense in a fire. And there most likely was an electrical fire,” he said.

“In the case of a fire, the first response is to pull the main busses and restore circuits one by one until you have isolated the bad one. If they pulled the busses, the plane would go silent.

“It probably was a serious event and the flight crew was occupied with controlling the plane and trying to fight the fire. Aviate, navigate, and lastly, communicate is the mantra in such situations.”

Family members of passengers from the missing Malaysia Airlines flight MH370 wait for news at the Lido Hotel. Photo: Getty Images

He also pointed to the landing gear as being a potential place where a fire could have occurred.

“What I think happened is the flight crew was overcome by smoke and the plane continued on the heading, probably on George (autopilot), until it ran out of fuel or the fire destroyed the control surfaces and it crashed.

“You will find it along that route — looking elsewhere is pointless.”

Goodfellow also blasted speculation that the plane was hijacked or that the pilots were somehow involved.

“There is no point speculating further until more evidence surfaces, but in the meantime it serves no purpose to malign pilots who well may have been in a struggle to save this aircraft from a fire or other serious mechanical issue,” he said.

“Captain Zaharie Ahmad Shah was a hero struggling with an impossible situation trying to get that plane to Langkawi. There is no doubt in my mind.”

However, his theory has been discredited by other aviation experts who said that even in a situation like that there were ways to get a distress signal out.

Australia is leading the hunt for missing Malaysia Airlines flight MH370 along the southern search corridor. Photo: AP

“I’ve seen those remarks. I’ve seen the articles. If there was an electrical fire on board, there still has to be a source,” former crash investigator Greg Feith told NBC News.

“And you can’t take out the entire electrical system all in one fell swoop without really catastrophically compromising the structure of the aeroplane.

“Typically, with an electrical fire, you’ll have smoke before you have fire. You can do some troubleshooting. And if the systems are still up and running, you can get off a mayday call.”